The performance metric for comparing the RT Boxes is the average execution time per core. For the RT Box 1 and the single core operation of RT Boxes 2 and 3, this means only one core is calculating the complete model. In the case of RT Boxes 2 and 3’s multicore operation, the total average execution time is calculated from the average execution time of each of the three available simulation cores.
To compare the performance of the RT Boxes, a modular multilevel converter (MMC) model is used. With new Task Frames on version 4.4 of PLECS, the user can split the system into different parts to run them on a single or multiple cores, as well as easily scale the number of cells in the converter. The model is open-loop controlled with the switching signals generated by another RT Box.
The MMC has a configurable number of sub-cells per arm that all contain a full-bridge, a DC capacitor and a non-ideal DC voltage input. Given a number of cells (N) per arm, the total number of switching devices in this converter is 24 x N.
RT Boxes 1 and 2 are able to simulate up to 5 cells with its 32 digital inputs. RT Box 3 is able to simulate up to 10 cells per arm as it has 64 digital inputs.
There is a clear performance gain with the 1.5 GHz processor in RT Boxes 2 and 3 over the 1 GHz processor in RT Box 1. Another significant performance gain is achieved by running the plant model on different simulation cores of RT Boxes 2 and 3.